1. Field of the Invention
The present invention relates to a photomagnetic disc record/reproduction apparatus using a recording medium housed within a cartridge, and more particularly to a cartridge loading mechanism and a magnetic head lifting mechanism used by such a photomagnetic disc record/reproduction apparatus.
2. Related Background Art
A mini-disc (MD) known as a rewritable photomagnetic disc includes a pre-mastered mini-disc and a recordable mini-disc. A pre-mastered mini-disc is a reproduction-only disc in which information is recorded in the form of pits and is reproduced from a reflected laser spot supplied by an optical pickup.
A recordable mini-disc is formed with a pit information record area at the central area of the disc and a recordable area at the outer area. The recordable area includes a user's TOC (Table of Contents) area (UTOC) and a program area. The recordable area has no pit, but a groove is engraved for the guidance to tracks. Information is recorded in the recordable area along the groove.
The groove sways like wobble. The rotation of the disc is controlled by a signal having an average frequency of 22.05 kHz and generated based on the wobble. Absolute addresses relative to the record start position are FM-modulated and recorded in the wobble.
Data record is achieved by magnetizing a magnetic film. Namely, the magnetic film is heated to a Curie point or higher by a laser spot while applying a magnetic field which reverses its polarity depending upon an input signal, and thereafter cooled. The signal is therefore recorded in the magnetic film as a change in the magnetization direction. The rotation direction of a polarization plane of a reflected laser spot changes with the magnetization direction of the magnetic film. Information is therefore reproduced by detecting a change in the polarization plane of a reflected laser spot.
A hole is formed in a cartridge accommodating a pre-mastered optical disc at a predetermined area for the inhibition of data record. A similar hole is also formed in a cartridge accommodating a recordable photomagnetic disc, and a shutter is provided to cover the hole. If the data record of a recordable photomagnetic disc is to be inhibited, the shutter is opened, whereas if the data record is permitted, the shutter is closed.
With a conventional photomagnetic disc record/reproduction apparatus, a hole indicating an inhibition of data record is detected to judge whether the data record is inhibited or not. When a photomagnetic disc allowed to record data is loaded, the magnetic head is always made to contact the disc.
With such a conventional photomagnetic disc record/reproduction apparatus, since the magnetic head is maintained always in contact with the disc permitted the data record even during the reproduction of data, the abrasion amount of the disc and magnetic head becomes great, shortening the life time of these components.
Furthermore, since there is a contact resistance between the disc and magnetic head, the load on the spindle motor increases resulting in a large power consumption of a battery if the apparatus is powered from the battery.
The present invention has been made in consideration of the above circumstances. It is an object of the present invention to provide a photomagnetic disc record/reproduction apparatus capable of elongating the life time of a magnetic head and disc, and the life time a battery when the apparatus is powered from the battery.
A mini-disc is accommodated within a cartridge. For the data record/reproduction, the cartridge is loaded to a record/reproduction unit. The record/reproduction unit is constructed of a turntable for rotating a disc, an optical pickup, a magnetic head, and the like. These components are mounted on a floating chassis in order to absorb external vibrations.
A recess is formed in a cartridge accommodating a pre-mastered mini-disc at a predetermined area. A pre-mastered mini-disc can be discriminated from a recordable mini-disc by detecting this recess. When a recordable mini-disc is loaded, the magnetic head is made to contact the disc, whereas when a pre-mastered mini-disc is loaded, the magnetic head is made not to contact the disc.
Of conventional mini-disc record/reproduction apparatuses for the record/reproduction of data of such a mini-disc, there is an apparatus of the type that a member for clamping a cartridge to a positioning member is mounted on a chassis supported by a main frame chassis of a loading mechanism. With such an apparatus, the record/reproduction unit cannot be physically separated completely from the main frame chassis during the data record/reproduction so that resistance against vibrations is adversely affected.
With an apparatus having a clamp member mounted on a holder for holding a cartridge, the friction when a cartridge is pushed into the holder becomes large, posing the problems of a large loading force and abrasion or damages of a cartridge.
Of conventional apparatuses having a lifting mechanism for lifting or lowering a magnetic head which follows the motion of an optical head, there are an apparatus of the type that the magnetic head lifting mechanism is not mounted on an optical pickup transport, and an apparatus of the type that the mechanism is mounted on the transport. In the former case, there occurs a contact or slide of a component during the motion of the optical pickup, generating vibrations, In the latter case, a drive source different from that of the loading mechanism is required for the optical pickup transport, increasing the necessary mount space and manufacturing cost.
The present invention has been made in consideration of the above circumstances. It is an object of the present invention to provide a photomagnetic disc record/reproduction apparatus capable of providing a good vibration-proof by physically separating a record/reproduction unit completely from a main frame chassis, eliminating a contact or slide of a component mounted on a magnetic head lifting mechanism during the motion of an optical pickup, driving the magnetic head lifting mechanism by a drive source of a loading mechanism, and realizing a reduced mount space and manufacturing cost.